Intermediate telegraph set for duplex lines



Patented Feb. 15, 392?.

rennet st easts "5 rat JOSEPH HERMAN, or new YORK, N. Y., assrenoa'ro AManrcan' TELEPHONE Ann TELEGRAPH CO PANY, a. CORPORATION 02: NEW YORK. I

INTERMEDIATE TELEGRAPH SET FOR DUPLEX LINES.

Application filed November 22, 1924. Serial No. 751,605.

This invention relates to duplex telegraph circuits and more particularly to improvements in intermediate telegraph sets for use with such circuits. V

The intermediate telegraph set of this invention will, when associated with a duplex circuit, provide full duplex reception from either of the terminal stations and half duplex transmission to either of said stations. It is especially useful for monitoring purposes and effects consid rable economies in equipment over previous arrangements. The intermediate set gives improved quality in the signals received and also-has very little effect upon the telegraph circuit with which it is associated[ and objects of the invention will appear more fully from the detailed description hereinafter given.

The invention may be more fully understood from the following description together with the accompanying drawing in the, Figures 1 and 20f which are illustrated circultdiagrams of the arrangements of the invention.

In Fig. 1 are shown two telegraph stations A and B interconnected by a line L. These terminal stations are provided with full duplex equipment. At station A is} shown a transmitting relay 1 controlled by the key K and operating its armature to transmit signals outove'r the line A receiving relay 2 iss hown and. a balancing artificial line N Therelay 2 by its armature controls circuit 3 in'which is included a sounder 4 for the reception of the signals.- At static-n B is provided Similar equipment comprising a key 'K' controlling the transmitting relay 5' and a receivingrelay 6 controlling the circuit .7 and the sounder 8.1

The intermediate set is shown as located at anywdesired position in the line and the apparatus therefor is included within the dotted lines. The receiving apparatus of the intermediate set consists of two polar These relays :each have relays 9 and 11. two windings and these windings are connected differentially into the circuit in op- The relay 9 has an artificial line '10 connected from the end of'one of its windings'to ground. The relayll has an artificial line12 connected fromg the end of One of its windings toround.- By proper adjustment of these artificial linesthe receiving relays can be made Further features responsive to signals from only one of'the terminal stations and will not be affected by signals from the other station. As this is a well known principle of duplex balance no further description thereof will be given. Instead of repeating the signals by connecting the receiving relay armature of oneof" the relays to the apex of the windings of the other relay and using positive and nega-' tive batteries on'the relay contacts, as would be done in a direct point repeater, the two a-peXes of the relay windingsare' connected directly together. As a result, one winding of each relay is connected to ground through its artificial line andthe other wind ing is in series with the line. In order to avoid an appreciable effect upon the terminal setsat the stations A and 13 due to the ground connection through the two artificial lines, 10 and 12, the windings of the receiving relays 9' and 11 have an unequal turn ratio. One winding of each-relay will i have a-small number of turns and will be made as-sm'all as desirable byv choosing a suitable-turn ratio for the two relay wind? I ings. The armatures and contacts ofthe two receiving relays 9 and 11 control the separate sounders 15 and-16 respectively, so that the simultaneous transmission from the two terminal stations may be observed. The switches S, and are connected to the relay-contacts so that the receivedvsignals may be reversed in case the batteries at the terminal stations arereversed.

To transmit from the intermediate set the key K is operated. This operates the two sounders 15 and 16, and: the transmitting relay 13, all of which are connected to the local battery 14. If batteries of like polarity are used for marking andspacing at the terminal stations, the line current will be zero when the sending keys K and K at -theter minal stations are closed] In this casethe line must be grounded at the intermediate station to transmit a spacing signal to'the terminals. For this condition the switch S 1.

is closed as shown on the drawing. The. closing of switch S connects aground tothe line. .Accordingly, the line circuit Vili spacingcontact of relay 13. Accordingly, when the key 'K islopened, a ground will be applied'to'the' line and a spacing signal sent to the terminal stations. It ispointed out that the armature'and marking contact oi relay 13 are connected together and to the be normal when the 'key K, is closed and through transmission can take place. When 'the'batterie s at one of the terminal stations are reversed, the line current will have its full-value when the sending keys K and K,

atdthe termi-nal stations are closed. Under these-conditions the switchS, is leftopen and the operation'ott'rela 13 will then open I the lme :for a spacing signal andclose 1t tor a -marki11 signal. 7 l

It. is pointed out that the operation or the sending relay 13'willnot operate either or then-receiving;relays9 and 11 under any of the above: conditions provided a; good balance'has beelrobtained :by means of the artificialwline'slO and 12. These relays, as'has beenpointed out,'are affected only by a reversal iof battery at the terminal stations A a:nd:B. .Accordingly, it is possible to trans mit ar-break signal to the: intermediate set from eithe'r'term-inalstation. Such a break signalw will be noticeable by the failure of 7 one or. both of the sound-ere 15 and 16 to operate while-signals are being transmitted I bymeans'ofthe-key K This failure is due to'the-operation of the receiving .relays 9 and '11 by'the'opening of the sending keys'at the terminal stations and indicates a desire ofthe operator at the terminalstation to inter-rnptihe operatorwat the intermediate set-V e V In Fig, 21's shown an alternative arrangement ofthe intermediate set of the invention 'inewhichathe-receiving relays 9: and 11 instead ofbeing-showaas of the differential 4'5.

duplex type,.are shown as of the bridge duplex type. In the.- differentialduplex type the ratio arms consist of therelay windings themselves. In: the. bridge type the ratio arms are impedanees r and R, and 1" and V Rfland ar-efof uneven ratio. The impedances I jR-andR would be large with respect tor and r.- This is to cause the impedance .of

i the balancing artificial lines. to be considerably larger than the sections ot' th-e lines bala-nced so that the effect upon the attenuation andline impedance will be: small." The principles'ofoperation will bathe same here 1 men ts {of Fig. 1'.

toforeexplained, with respect to the arrange- 7 Similar reference charactersdenote. like partsin; both figures of the drawing. I

1 While the invention has been disclosed in certain specific arrangements which lrdeemedvdesirable, it is understood that it is capable of/emhodiment inm ny and widely varied formswithout departing from the spirit of the invention asv defined by the appended claims. 1

What is claimed is:

1. A; duplex telegraph system comprising two terminal stations, a line interconnecting said stations, and an intermediate set associated with saidline, said intermediate set 1 including t-wo receiving relays each having two windings, one winding of each relay being: connected serially in the line and; the" other windings being connected to ground through variable balancing artificial .alines,

said windings. of each relay having difierent turn ratios. I

:2. A duplex telegraph system comprising two terminal statiens,a line interconnecting said: stations, I-andan intermediate set as so ciated with said line, said.intermediate set including two receiving relays each having two windings, the apexes of the-windings ot' each-of said relays-being connected together, the windings of said relays beingnssociated with the llIlBlSO: as. to be differentially arranged with respect to currents transmitted oversaid line in-opposite directions andhaving unequal turn ratios, and variable balancing artificial lines associated with said relay windings.

3. A duplex telegraph system comprising two terminal. stations, a line-interconnecting said stations, .and an intermediate set asso- '(llatetl' with said l1ne,, said lntermedlateset including two receiving. relays.- each having two windings, the apexes of the windings oi each of said relays bein connected together, the windings otsaid re ays-being. associated with the line so as to be difierenti'allyaarsaid stations, and an intermediate set associated with said liner-said intermediate set including two receiving relays each havingtwo windings, theapexes of .the'windin-gs of each of sa d relays being connected together, the windlngs .of said relays .belng associated ranged with respect to currents transmitted over said 'llne n OPPOSItG ClII'QGtIOIIS-11nd;V

with the line so as to be diflerentiallyrar ranged with respect to-currents transmitted over said line in opposite directions and 7 having unequal turn ratios, variable balanc ing artificial lines associated with-said relay windings, a transmitting circuit includ mg a transmitting relay atisaid intermediate set, switching means whereby said line may be opened or grounded-by said: transmitting relay, andrsignal responsive devices under the joint control of said receiving relays and said transmitting circuit.

5. A duplex telegraph system comprising two terminal stations, a line interconnecting said stations, and an intermediate set associated with said line, said intermediate set including two duplex receiving relays each having two ratio arms of unequal impedance, one rat-i0 arm of each relay being connected serially in the line and the other ratio arms being connected to ground through variable balancing artificial lines.

6. A duplex telegraph system comprising two terminal stations,a line interconnecting said stations, and an intermediate set asso-' ciated with said line, said intermediate set including two duplex receiving relays each having tWo ratio arms of unequal imped-,

ance, the apexes of the ratio arms of each of said duplex receiving relays being connected together. 7

7. A duplextelegraph system comprlslng two terminal stations, at line interconnecting said stations, and an intermediate set asso- November 1924.

ciated with said line, said intermediate set including two duplex receiving relays each having two ratio'arms, the apexesof the ratio arms of each of said duplex receiving relays being connected together, one of the ratio arms of each of said relays having a greater impedance than the other ratio arm 7 ground said stations, and an intermediate set asso ciated with said line, said intermediate set lncluding two duplex receiving windings pedance, the ratioarms of lesser impedance of each relay being'connected serially in said line and the ratio arms of greater impedance of-each relay being connected to ground through variable balancing'artificial lines.

' Intestimony whereof, I have signed my name to this specification this 18th day of JOSEPH HERMAN. 7

each having two ratio arms of unequal im 

